The following are the changes I would make, since he's pretty much worthless outside of niche situations at the moment.
1: The most important one, that we can all agree on, is that his gas SHOULD NOT AFFECT TEAMMATES AT ALL. It's unbelievable that there's a legend that, in a team-based game with no TKing, can negatively impact his own team simply by using his only abilities. And it's not a small inconvenience, if your teammates are caught in your gas and the enemies aren't, you just lost that fight 9 times out of 10. Needs to be fixed as soon as possible, because this is the main thing keeping him from being viable imho.
2: Slightly increase the radius of his ultimate gas, or slightly increase its damage. (Either 5 yards more or 3 more damage per tick.)
3: Increase the range at which he can throw traps very slightly, as a lot of the time even throwing a trap onto the roof of a 1 story building is impossible, even if you're near the roof.
Even with these changes I don't think he would be meta, but he wouldn't be an anchor holding your team back from a win because he threw his ult wrong.
